TOKYO - A GROUP of Asian women forced to work as sex slaves for Japan's soldiers during World War II urged the country's lawmakers on Tuesday to pass a resolution demanding an official apology.

'Survivors are quickly ageing, still suffering from pain and complications from damage in the days of sexual slavery,' said a statement from a committee representing the so-called 'comfort women' and their families.

'Due to the delay to an apology and compensation by the Japanese government, the situation has become even more painful for the survivors,' it said.

The group is calling for a fact-finding body, an official apology and state compensation for victims, as well as the inclusion of historical facts in school textbooks.

Japan has apologised for the military's involvement in crimes against the sex slaves - which it has euphemistically referred to as 'comfort women' - but it has denied responsibility for running a system of military brothels.

Last year then premier Shinzo Abe triggered uproar when he said there was no evidence Japan directly coerced women into sexual slavery, although he later renewed an apology to them.

Ms Lee Soo-San, 80, said she still suffers physical and emotional pain after being forcefully put into a military brothel at the age of 16 in what was then Japanese-controlled Manchuria.

'Military men were standing in a long line in front of the room (where she was imprisoned). I did not think I could ever survive,' she said.

When she became pregnant, a military doctor forced her to abort, and removed her entire womb. 'My body is damaged and full of scars,' she said.

The US and Canadian parliaments last year called for a fresh apology from Japan for forcing women into sexual slavery.

Historians say up to 200,000 young women, mostly from Korea but also from China, Indonesia, the Philippines and Taiwan, were forced to serve as sex slaves in Japanese army brothels.